Cataract surgery remains the most common surgical
procedure in the United States, with over 2 million performed yearly.1,2
Many of these patients have concomitant retinal disease, which may influence the
decision to recommend surgery and may limit the ultimate visual outcome. Certain
retinal diseases may be exacerbated by cataract surgery, although the peer-reviewed
evidence for this risk is controversial.

In this article, general principles regarding the evaluation
of the cataract patient with retinal disease are reviewed. Current recommendations
regarding cataract surgery for 3 common groups of retinal patients are targeted:
those with diabetic macular edema (DME), age-related macular degeneration (AMD),
and peripheral retinal disease.

Rather than any particular surgical complication, a not uncommon
cause of a disappointing visual result following cataract surgery is unrecognized
retinal disease. Therefore, identifying concomitant retinal pathology, which may
be subtle, is an important part of the preoperative evaluation as well as the informed
consent.

It may be difficult to discriminate between vision loss from cataract
and vision loss from retinal pathology. Although potential acuity meter (PAM) testing
is frequently helpful, various tests of reading performance may also give useful
information.3

In patients with more advanced cataract, ophthalmoscopy as well
as fundus photography and fluorescein angiography may be hindered to variable degrees.
Optical coherence tomography (OCT) may give surprisingly good images through relatively
small pupils and moderately dense lens opacities (Figure 1). OCT is invaluable in
patients with an abnormal-appearing macula who are considering cataract surgery.
Other testing (such as fluorescein or indocyanine green angiography) may be used,
but are not generally used as a screening tool.

In patients with very dense cataract, precluding a good view of
fundus details, B-scan echography is generally indicated, primarily to rule out
retinal detachment (RD) or other advanced posterior-segment disease (Figure 2).
In addition, examination of the fellow eye, when possible, may offer important clues
(for example, the presence of macular drusen, diabetic retinopathy, and other conditions).
The presence of a relative afferent pupillary defect in the cataractous eye may
also indicate advanced retinopathy and/or optic neuropathy.

Previous pars plana vitrectomy (PPV) is a risk factor for complicated
cataract surgery due to many factors, including abnormal fluctuations in anterior
chamber depth.4 The anterior-segment
surgeon should be prepared for capsular rupture and posterior dislocation of lens
fragments in these patients. When evaluating patients with macular hole or epiretinal
membrane, consideration should be given to cataract surgery either prior to, or
concomitant with, PPV.

Recommendations from the peer-reviewed data regarding the risk
of DME progression following cataract surgery are inconsistent. In the pseudophakic
eye, the distinction between DME and pseudophakic (Irvine-Gass) cystoid macular
edema (CME) may be difficult. Nevertheless, multiple retrospective studies and small
case series have reported an increased risk of progression of diabetic retinopathy,
including macular edema, following cataract surgery.5-7
On the other hand, the Early Treatment Diabetic Retinopathy Study Report Number
258 reported: "No statistically
significant long-term increased risk of macular edema was documented after lens
surgery."

It appears prudent to stabilize any pre-existing diabetic retinopathy
prior to elective cataract surgery. Treatment of clinically significant macular
edema with photocoagulation or other means (for example, intravitreal triamcinolone
acetonide or bevacizumab), prior to cataract surgery, is generally recommended.
Similarly, proliferative diabetic retinopathy and CME due to retinal vein occlusions
are usually treated, as appropriate, prior to cataract surgery. Ideally, cataract
surgery can be delayed until OCT demonstrates improvement of macular edema.

In patients with dense cataract, photocoagulation may not be possible.
In this circumstance, treatment may be applied several weeks after cataract surgery,
once the incision has healed sufficiently to allow placement of a contact lens.

AGE-RELATED MACULAR DEGENERATION (AMD)

Similar to DME, the true risk of progression of AMD following
cataract surgery is controversial. Pooled data from 3 large population-based studies
indicate a correlation between late AMD (choroidal neovascularization [CNV] or geographic
atrophy) and a history of cataract surgery, although the authors of this study emphasized
that this finding does not necessarily imply a causal link.9
At the present time, unpublished data from the Age-Related Eye Disease Study
show "no definite increased risk of either CNV or geographic atrophy following
cataract surgery" (F. Ferris, personal communication).

Occult CNV may be under-recognized in this population. Some patients
with CNV lack ophthalmoscopically obvious subretinal fluid, hemorrhage, or lipid
exudate, particularly when viewed through a moderately dense cataract. In this setting,
OCT is very helpful in identifying CME, subretinal fluid, or sub-retinal pigment
epithelial fluid, indicating wet AMD.

Patients with CNV are generally treated prior to cataract surgery,
using pegaptanib, bevacizumab, verteporfin, photocoagulation, or other agents as
appropriate. Similar to DME, delaying cataract surgery until the OCT indicates improvement
of CME and/or subretinal fluid is usually recommended.

Independent risk factors for rhegmatogenous RD following cataract
surgery include prior history of RD, Nd:YAG capsulotomy, lattice degeneration, increased
axial length, myopia, and ocular trauma.10
The 4-year cumulative risk of RD following cataract surgery is probably less than
1%.11 Theoretically, the
risk is lower in eyes with a pre-existing posterior vitreous detachment.

In the setting of a dense cataract with a rhegmatogenous retinal
detachment, PPV with concomitant pars plana lensectomy is generally recommended.
The decision to place an intraocular lens at the time of surgery is individualized
for each patient.

CONCLUSIONS

In general, retinal diseases with the potential for progression
such as DME, CNV, and retinal tears are evaluated and treated, when possible, prior
to cataract surgery. Patients with visually significant lens opacities, and stable
retinal conditions should be offered cataract surgery when, in the judgment of the
physician, they are likely to benefit. Following these general principles, reasonable
patient expectations can be emphasized, to avoid the surprise of a less-than-perfect
visual outcome from cataract surgery.